Yes, we can pass the Block as argument in function. Here it is :

let suppose i create a class Downloader

First declare a Block in Downloader.h:

typedef void (^DownloadComplete)(double,double,double,BOOL,id,id);

then declare method as following in Downloader.m:

-(void)startdownload:(id)Object andCompletion:(DownloadComplete)completion;

And here it is implementation :

-(void)startdownload:(id)Object andCompletion:(DownloadComplete)completion{
// here will come you logic and other formation after that simply call the block
    completion(0,0,0,YES,response,Object);
}

And in this way we can call that method in which Block as function argument:

Downloader *downloader=[[Downloader alloc] init];
[downloader startdownload:self andCompletion:^(double bytesread, double totalBytesRead, double totalBytesExpectedToRead, BOOL flag, id object, id object) {

// Here you can handle the response and do what you want to do with it.

}